U.S. Pat. No. 5,306,210 discloses a louver type roof structure including a plurality of parallel slats 10 mounted on hinges 11 which in turn are mounted on carrier beams 12 (FIG. 1). Each hinge comprises a base lever 16 and a body 14-15 with a free lever 18, rotatably connected to each other. The hinges are mounted to the carrier beams 12 by the base lever securable to the carrier beam in a selected position. The slats have characteristic profile with an upturn 4 and channel 2 at one edge, a downturn 3 and channel 1 at the other edge, both channels being open towards the underside of the slat. The hinges are secured to the slats by snapping the hinge body ends 14 and 15 into the channels without penetrating the slat. The free levers 18 of the hinges are rotatably connected to a movable rod 22 such as to provide synchronous pivoting of the slats between a closed position in which the slats are disposed in a roughly coplanar orientation (indicated by broken lines), and an open position in which the slats are disposed in spaced apart generally parallel planes. In the open position, the louver roof provides access for the sunlight and air currents, while in the closed position the roof provides shade and/or protection against rainfall.
Pergolas of the same louver type are produced by Pas-Cal™ (FIG. 2, functionally similar parts have the same numbers as in FIG. 1). The hinge 11 in these pergolas however constitutes a single integral body 14-15 made of plastic, while the base lever 16 is integral with a carrying beam 24. The hinge has lugs (axles) 20 rotatably mounted directly in the carrying beams 24 which have a U-shaped cross-section allowing elastic opening when the lugs are snapped in place.
The axes of hinge rotation in both above designs are disposed approximately under the middle of the slat profile. The slats are pivotable by 45-70° between the closed position and the extreme open position.
AU-B-33573/84 discloses a louver type roof structure comprising a support frame and a plurality of slats (louvers). The slats have box-like profile for rigidity as they are supported only at their ends. The axis of rotation is usually within the profile and the range of rotation may be close to 180° as there are no intermediate supports.